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666 Cards in this Set

  • Front
  • Back
carbonyl and amine
geminal dihalide
carbon with two halogens bonded to it
vicinal dihalide
two adjacent carbons both bonded to halogens
carbon with an -OH and -OR group along with one -R group
carbon with an -OH and -OR group along with two -R groups
mesyl group
sulfur with single bonded methyl group and two double bonded oxygens
tosyl group
sulfur with single bond to aromatic cyclohexane group and two double bonded oxygens
acetyl group
carbon with a carbonyl group as well as a terminal methyl group
acyl group
carbon with a carbonyl group and an R group
anhydride group
Two carbons each connected to R groups as well as carbonyls, connected together via an oxygen
aryl group
aromatic cyclohexane
benzyl group
aromatic cyclohexane bonded to a methyl group
two nitrogens bonded together via single bonds
nitrogen double bonded to an R group as well as a single bond to another nitrogen
vinyl group
two double bonded carbons
vinylic group
two double bonded carbons with a halogen bonded to one
two double bonded carbons with a methyl group bonded to one
carbon triple bonded to a nitrogen
carbon single bonded to an R group and single bonded to an NRH, and double bonded to a CR2.
a tautomer of en enamine, wherein the double previously double bonded CR2 group's double bond shifts to a single bond, providing electrons for a C=N-R group to be created
carbon single bonded to two R groups, and a =N-OH group.
carbon single bonded to one oxygen and double bonded to another
a nitrogen double bonded to an oxygen
conformational isomers
different spatial arrangements of the same molecule. rotations around a sigma-bond
structural isomers
same molecular formula but different bond-to-bond connectivity
molecules that differ in reflections
exactly the same reflections of molecules
rotates plane polarized light clockwise
rotates plane polarized light counter clockwise
two molecules with the same molecular formula and the same bond-to-bond connectivity that are not the same compound
what are two examples of stereoisomers?
enantiomers and diastereomers
what is resolution?
the separation of enantiomers
how do enantiomers relate chemically and physically?
they have the same chemical and physical characteristics except with reactions with other chiral compounds and reactions with polarized light
what are diastereomers?
they have the same molecular formula, have the same bond-to-bond connectivity, are not mirror images of eachother and are not the same compound
what is a geometric isomer?
they exist due to hindered rotation about a bond. Cis-isomers and Trans-isomers are examples
Do geometric isomers have different physical properties?
Yes they do.
Which, cis or trans, have a dipole moment?
cis has a dipole moment, while trans does not.
Which has stronger intermolecular forces?
Cis has stronger forces due to the dipole moment.
What does stronger intermolecular forces pertaining to geometric isomers infer about their physical properties?
Cis molecules have higher boiling points
What does a lack of symmetry among cis molecules infer about their physical properties?
They are unable to form crystals as readily due to their lack of stackability
Which has higher heats of combustion due to steric hindrance?
Cis molecules have higher heats of combustion because they have higher energy levels due to steric hindrance
Do diastereomers have different physical properties?
They have different rotation of plane-polarized light, as well as different melting and boiling points as well as solubilities.
What is the maximum number of optically active isomers found via?
The equation is 2^n, where n is the number of chiral centers
What are meso compounds?
They are compounds where two chiral centers can offset eachother creating an optically inactive molecule
Are meso compounds achiral?
Why are meso compounds considered achiral?
Because they have an internal plane of symmetry
What are epimers?
They are diastereomers that differ at only one chiral carbon
What are anomers?
They are the two possible diastereomers that form during an epimeric ring closure.
What is the chiral carbon of an anomer called?
Anomeric carbon
When the hydroxyl group on the anomeric carbon on glucose is oriented in the opposite direction to the methyl group, what is the anomer labeled as?
What about when the hydroxyl group is in the same direction?
It is labeled beta.
What governs boiling point trends in alkanes?
Intermolecular forces
When carbons are added to a single chain alkane, the molecular weight goes up increases intermolecular forces concurrently. What happens to the boiling point?
It goes up.
What does branching do to boiling point in alkanes?
It lowers the boiling point
Does melting point go up or down in alkanes with increased molecular weight?
It goes up
What does branching due to melting point of alkanes?
It increases it
Are alkanes soluble in water?
What are alkanes soluble in?
They are solube in benzene, carbon tetrachloride, chloroform, and other hydrocarbons
If an alkane contains a polar functional group, what happens to the polarity of the entire molecule and its solubility as the carbon chain is lengthened?
It goes down
Do alkanes have low density?
What happens during combustion?
An alkane reacts with oxygen, producing CO2, H2O and most importantly heat
Is combustion spontaneous?
No, it requires heat to occur, usually via a flame.
What type of reaction is combustion?
It is a radical reaction
If a molecule has a high heat of combustion, is it more or less stable than a similar molecule with a smaller heat of combustion?
A high heat of combustion correlates to the energy level of a molecule, inferring a less stable molecule
What happens if you react an alkane with F, Cl, and Br in the presence of heat or light?
Well what happens first in halogenation?
The first step is initiation.
What happens during initiation?
Light or heat cleaves a covalent bond between a two bound halogens. They both split leaving two identical radicals
What happens to these radicals after that, and what is the step called?
The next step is called propagation, and what happens is the halogen radical removes a hydrogen from the alkane, resulting in an alkyl radical.
What can this alkyl radical do to get rid of its radicalness?
It can hookup with a diatomic halogen molecule creating an alkyl halide and a new halogen radical.
Is this the end of our halo-radicals?
No! This reaction can continue indefinately, or it can go through the third and final step of halogenation.
What the third and final step of halogenation?
So what exactly happens in the termination step of halogenation?
Several things could happen. Two akyl radicals could react, the last halo-radicals can react with alkyl-radicals to form alkyl halides, or two halo-radicals can hookup
Is halogenation an endothermic or exothermic process?
It is exothermic
What is the stability chart for an alkyl radical?
What type of geometry do alkyl radicals exhibit?
They exhibit trigonal planar geometry
When is the majority of product formed during halogenation?
The majority of the alkyl halides are formed during propagation
Are Pi-bonds more or less stable than Sigma-bonds?
They are less stable
Does this mean alkenes are more or less reactive than alkanes?
They are more reactive.
When dealing with alkenes, what should I keep in mind about the Pi-bonds?
They are electron hungry
What does this infer about acidity values of alkenes versus alkanes?
Alkenes are more acidic as a result of the willingness to gain electrons
What happens when a proton is moved away from a Pi-bond?
The Pi-bond of the alkene absorbs some of the negative charge
What does this do to the conjugate base?
It stabilizes it
How does substitution relate to thermodynamic stability of alkenes?
They more highly substituted, the more stable the alkene.
You're wrong! How come when you have addition reactions dealing with electrophiles the most substituted are the most reactive, it should be the opposite right?
Well a paradox exists due to the carbocation intermediate. A tertiary alkene will be a more stable carbocation, so it will proceed with greater frequency.
So which is right?
When dealing with electrophilic addition reactions of alkenes, the most reactive are the more substitituted
How do physical properties of alkenes work?
They work the same way as alkanes
Are alkenes soluble in water?
Slightly, and they have a lower density than water.
Which is more acidic, alkanes or alkenes?
What happens in an elimination reaction?
One or two functional groups are eliminated or removed to form a double bond.
What type of reaction is dehydration of an alcohol?
It is an E1 reaction
What happens in dehydration of alcohol reactions?
An alcohol forms an alkene in the presence of hot concentrated acid
Since it's an E1 reaction, that means it depends on the concentration of only one reactant, but which reactant does it depend on, the acid or the alcohol?
It depends on the concentration of the alcohol in this case.
What happens in the first step of dehydration of alcohols?
The acid protonates the hydroxyl group
What does this produce, and what was the purpose of protonating this new thing?
It produces water, which is a good leaving group. It wants to dump off the compound.
What happens next, and whats so special about this step?
This is the rate-determining step- the water drops off, forming a carbocation
Woo, carbocation. When I see carbocation I should think what?
Rearrangement possibilities exist, and stability of intermediate
What does carbocation stability follow the trend of?
It follows th same trend as radical stability?
What's that trend again?
So when would rearrangement occur?
It would only occur if a more stable carbocation could be made
What happens in the final step of dehydration of an alcohol?
A water molecule deprotonates the carbocation and the alkene is formed
What will the predominant product be a result of?
It will be the more stable, most substituted alkene.
What does the Saytzeff rule say?
It says that the major product of elimination will be the most substituted alkene.
What is dehydrohalogenation?
It's what happens when you take an alkane with a halogen and dump the halogen off in favor of making an alkene.
What are the two possibility routes for dehydrohalogenation to occur?
It can occur via E1 or E2
When would dehydrohalogenation occur via E1?
It would happen if a strong base is there
When would dehydrohalogenation occur via E2?
It would happen is there is a high concentration of a strong, bulky base
What happens first in the E1 reaction?
The halogen drops off in the first step.
What happens second in the E1 reaction?
The hydrogen is removed in the second step via the weak power of our weak base.
So the E1 reaction is multi-step or single-step?
What happens in E2 reaction?
The base removed a proton from the carbon next to the halogen-containing carbon and the halogen drops off, leaving an alkene.
So is the E2 reaction single or multi-step?
It is single step.
What does the bulky base of this E2 mechanism prevent?
It prevents an SN2 reaction, but if the base is too bulky, the Saytzeff rule is violated, leaving the least substituted alkene.
So what's an important thing to notice about the difference between these two pertaining to the power of the bases?
Well the E2 mechanism has a strong base, and it's so pimped out that it can pull the hydrogen off even without the decreased stability of an intermediate state like what occurs in the E1 mechanism.
What type of reaction of catalytic hydrogenation?
It is an addition reaction?
What type of catalyst is used in catalytic hydrogenation?
A heterogenous catalyst
What type of addition occurs usually?
What are possible catalysts?
Ni, Pd, or Pt
So what actually happens?
You take an alkene and you turn it into an alkane
Is hydrogenation an endothermic or exothermic reaction?
It is an exothermic reaction.
Is it spontaneous?
No, it has a high energy of activation
What are heats of hydrogenation used to measure?
They are used to measure the relative stabilities is alkenes.
If something has a low heat of hydrogenation, is it unstable?
No it is considered stable
What happens with syn addition of an alkynes via hydrogenation?
It creases a cis alkene.
What does oxidation of an alkene produce?
It may produce glycols or it may cleave the alkene at the double bond
What is an example of a cleavage such as this?
If you add 1) O3 and 2) Zn,H2O, what happens to an alkene?
It will cleave the alkene at the double bond, producing two carbonyl groups
What happens to alkynes when they undergo ozonolysis?
They produce carboxylic acids
What is an electrophile?
It is an electron-loving species
What types of things are usually electrophiles?
Things with a positive charge, even if it is only from a momentary dipole.
What does the double bond of alkene function as pertaining to electrophiles?
It is an electron-rich environment, which will attract electrophiles
What rule is followed when you had a hydrogen halide to an alkene?
Markovnikov's rule
What does Markovnikov's rule state?
It states the hydrogen will add to the least substituted carbon of the double bond
What is the first step of electrophilic additition of a hydrogen halide to an alkene?
The hydrogen halide is a Bronsted-Lowry acid, so it will create a positively charged proton, which acts as an electrophile.
What is the second step of electrophilic additition of a hydrogen halide to an alkene?
The newly formed carbocation picks up the negatively charged halide ion.
Which is the slow step?
The first step is the slow step, and it determines the rate
What happens during this reaction is peroxide (ROOR) is present?
Bromine will add to the least substituted carbon
What is this known as?
Anti-markovnikov addition.
Will the other halides perform anti-markovnikov addition?
No, they still do Markovnikov, even in the presence of ROOR.
What are the most reactive alkenes, and why?
The most reactive are the most thermodynamically stable, because they also have the lowest activation energy and form carbocations the easiest.
What is hydration of an alkene?
It takes place when water is added to an alkene in the presence of an acid.
Does hydration of an alkene follow Markovnikov's rule?
Yes it does.
What is this reaction the reverse of?
It is the reverse of dehydration of an alcohol.
What circumstances drive an alkene toward alcohol formation?
Low temperatures and dilute acid
What circumstances drive an alcohol toward alkene formation?
High temperatures and concentrated acid
What is oxymercuration/demercuration?
It is another reaction which creates an alcohol from an alkene
Is oxymercuration/demurcuration a one or two step process?
Two step process
Does it usually result in rearrangement of the carbocation?
Very rarely.
What happens in the first step of oxymercuration/demurcuration?
The mercury-containing reagent partially dissociates to +Hg(OAc)
What does the +Hg(OAc) do once its formed?
It acts as an electrophile creating a mercurinium ion
What does water do to the mercurinium ion?
It attacks the mercurinium ion to form the organomercurial alcohol.
What type of addition is this?
What is the second step?
It is the demercuration to form the alcohol
How is this performed?
By the addition of a reducing agent and base.
What is hydroboration?
It is another mechanism to produce an alcohol from an alkene
Does it follow Markovnikov?
No, it is anti-markovnikov
What type of addition is it?
It is syn addition
So what happens in hydroboration?
Take an alkene and add a hydrogen and alcohol to the same side of two carbons, via anti-markovnikov.
What happens if you add Br2 or Cl2 to an alkene?
They add via anti-addition to form vicinal dihalides
What is an important difference between a similar reaction involving alkanes?
Oh, you mean halogenation, right? Well alkene halogenation doesn't require heat or light
What happens if you perform alkene halogenation in the presence of water?
Water will act as a nucleophile instead of a bromide/chloride ion.
What does this produce?
It produces an anti-addition halohydrin
Does benzene undergo addition or substition?
It only undergoes substitution
Is benzene flat?
Yes, it has to be considering its aromatic
What happens when an electron withdrawing group is in the R position of a benzene?
It deactivates the ring and directs any new substituents to the meta position
What do electron donating groups do to the wring?
They active the ring and direct any new substituents to the ortho and para positions.
What is the exception to this rule, and why?
Halogens are an exception because they are electron withdrawing and deactivate the ring as expected but they are ortho-para directors.
What are the strongly electron donating groups?
What are the moderately electron donating groups?
What are the weakly donating groups?
What are strongly electron withdrawing groups?
What are moderately withdrawing electron groups?
What are weakly withdrawing electron groups?
What is phenol?
It is a benzene with an alcohol substituent.
What is aniline?
It is a benzene with an amino substituent.
What is toluene?
It is a benzene with a methyl substituent..
What is benzoic acid?
It is a benzene with a carboxylic acid
What is nitrobenzene?
It is a benzene with a nitro group.
What happens in a substitution reaction?
One functional group replaces another.
How many steps does an Sn1 reaction have?
2 Steps
What is the rate of an Sn1 reaction dependent on?
The rate is dependent on one of the reactants
Is this the fast step?
No, it is the slow step.
Does this make it the rate determining step?
Yes it does.
Does the creation of a carbocation depend on the nucleophile?
Nope, because it attacks during the second step after the carbocation has been made.
So what does the rate of an Sn1 reaction depend on then?
It only depends on the concentration of the substrate.
What is the leaving group?
It is the group being replaced.
What happens if you perform an Sn1 reaction creating a carbocation from a chiral carbon?
You would get two products, both enantiomers of eachother other.
Why will both enantiomers be made?
They will both be made because the intermediate carbocation is planar, which allows the nucleophile to attack from both sides.
Can carbon skeleton rearrangement occur in an Sn1 reaction, and if so, under what circumstances?
It can occur if rearrangement produces a more stable form.
How can an E1 reaction accompany an Sn1 reaction?
It can because the nucleophile may act as a base to abstract a proton from the carbocation, forming a carbon-carbon double bond.
What type of substrate will most likely undergo an Sn1 reaction?
A more substituted substrate will because the carbocation produced will thus be more stable due to increased branching.
How many steps does an Sn2 reaction take place in?
1 step
What is the rate of an Sn2 reaction dependent on?
It is dependent on the concentration of both substrate and nucleophile.
What is the substrate in these reactions?
It is the electrophile or the molecule being attacked by the nucleophile.
How does the nucleophile attack the intact substrate in an Sn2 reaction?
It attacks it from behind the leaving group.
What does this cause as a result?
It causes an inversion of configuration
What type of substrate will hinder an Sn2 reaction, and why?
A more substituted substrate would hinder the reaction because the nucleophile wouldn't be able to attack from the rear as easily due to steric hindrance.
What could occur instead of an Sn2 reaction if the nucleophile is a strong base and substrate is very hindered?
An E2 reaction could occur
What happens in an E2 reaction?
The nucleophile acts as a base abstracting a proton and, in the same step, the halogen leaves the substrate forming a carbon-carbon double bond.
What else is another hindering factor when dealing with Sn2 reaction when pertaining to size of interacting molecules?
If the nucleophile is too bulky, the Sn2 reaction could be hindered.
Is a base a weaker or stronger nucleophile than its conjugate acid?
It is always a stronger nucleophile than its conjugate acid.
Well what determines if a substitution or elimination reaction will occur based upon basicity?
If a nucleophile behaves as a base, elimination results.
So how can we avoid an elimination reaction from occuring pertaining to nucleophiles if we want a substitution reaction take place?
Just use a less bulky nucleophile.
What do negative charge and polarizability do to nucleophilicity?
They add to it, increasing the likelyhood of electron donation.
What is the general trend concerning electronegativity dealing with nucleophilicity?
Electronegativity generally reduces nucleophilicity when going up and to the right on the periodic table
What are polar protic solvents?
They are solvents that can hydrogen bond.
What do polar protic solvents do to nucleophiles?
They stabilize them.
What do polar protic solvents do to carbocations?
They stabilize them.
Does a stable nucleophile speed or slow an Sn2 reaction?
It slows an Sn2 reaction down.
Does a stable carbocation increase or decrease the rate of Sn1 reactions?
It increases the rate of Sn1 reactions
So what's the takeaway for polar protic solvents concerning Sn1 and Sn2 reaction rates?
They increase Sn1 rate and decrease Sn2 rate.
What are polar aprotic solvents?
They can't hydrogen bond
Do they form strong or weak bonds with ions?
They form strong bonds with ions
What does this do to Sn1 and Sn2 reactions?
It increases the rate of Sn2 reactions while inhibiting Sn1 reactions
What would be the purpose of heating a solvent in substitution reactions?
This is sometimes done in Sn1 reactions in order to provide energy for the formation of the carbocation.
What is solvolysis?
The solvent acts as the nucleophile
What are the best leaving groups?
They best are those that are the most stable when they leave.
Generally speaking, how does the strength of the base determine leaving group stability?
Generally, the weaker the base, the better the leaving group.
How does electron withdrawing ability effect leaving group ability?
Generally, electron withdrawing groups are good leaving groups.
Is the leaving group going to be stronger or weaker than the nucleophile?
It will always be mor estable than the nucleophile
What type of physical trends to alcohol's follow?
They follow the same basic trends as alkanes.
What are those trends again?
The boiling point goes up with molecular weight and down with branching. The melting point also goes up with molecular weight.
Why are alcohol melting and boiling points much higher than alkanes?
They hydrogen bond, which increases intermolecular forces, which must be overcome to change phase.
Is a longer carbon-chain alcohol more or less soluble in water than a short carbon chain alcohol?
It is less soluble in water.
Are alcohol's more or less acidic than water?
They are more acidic than water.
What is the order of acidity for alcohols?
Why would increased substitution cause less acidity?
The more substituted, the stronger the oxygen and hydrogen bonds, due to the electron donating effects of carbons.
Is excess charge a stability or instability?
It is an instability.
So how does this relate to carbonds and alcohols?
The most stable conjugate base will have the weakest negative charge, and since carbons donate electrons, they increase the charge of the oxygen and alcohol inductively, effectively decreasing the stability of the conjugate base.
What can you do with an organometallic compound pertaining to alcohols?
You can synthesize an alcohol with one.
What do organometallic reagents possess?
They possess highly polarized carbon-metal bonds.
Which is more electronegative of the two bonds?
The carbon is more electronegative than the metal.
So which will be partially negatively charged?
The carbon will take a partial negative charge.
What does this make the organometallic reagent?
It makes it a strong nucleophile and base.
What is the most common organometallic reaction?
Nucleophilic attack on a carbonyl carbon.
This produces an alcohol after what type of bath?
An acid bath
What are the reagents known as?
Grignard reagents
What else do Grignard reagents react with?
They also react with C=N, NItrile, S=O, N=O.
What is the Grignard reagent a strong enough base to deprotonate?
It can deprotonate O-H, N-H, S-H, and an alkyne hydrogen.
What do Grignards require to form?
What happens if yuo add NaBH4 or LiAlH4 to a carbonyl?
In a mechanism similar to Grignard synthesis, a hydride reacts with carbonyls to form alcohols
What can be used to reduce aldehydes and ketones to alcohols via this method?
Both NaBH4 and LiAlH4 can be used.
What can be used to reduce esters and acetates to alcohols?
Only LiAlH4 is strong enough.
Why is it more difficult to reduce esters and acetates than ketones and aldehydes?
The group attached to the carbonyl of the ester or acetate is a stronger electron donor than an alkyl group or hydrogen
What does donating electrons more strongly have to do with reduction synthesis of an alcohol?
Well if something next to the carbonyl donates electrons more strongly, it will reduce the positive charge on the carbonyl carbon making it less attractive to the nucleophile
Most of the time on the MCAT, if an alcohol is a reactant what will be it be acting as?
A nucleophile
What do the two lone pairs of electrons on the oxygen do?
THey are pushed out by the bent shape, and they search for a positive charge.
What does this cause the oxygen to do?
It makes it want to find and connect to the substrate and the positively charged proton will drop off into solution.
What happens if an alcohol as a nucleophile attacks a double bonded substrate?
It can do a nucleophilic addition, just adding to the double bond making it a single bond.
What happens if an alcohol as a nucleophile attacks a single bonded substrate?
It will do a nucleophilic substitution.
What types of alcohols can be oxidized?
Primary and secondary alcohols can be oxidized
Can tertiary alcohols be oxidized?
Hell no, what would they be oxidized to? a quaternary alcohol?!
What are the things that can happen if something is oxidized?
It can involve a loss of H2
What are the things that can happen if something is reduced?
It can involve an addition of H2 or (H-)
What happens if you add or lose H+, H2O, HX, etc?
Neither oxidation nor reduction takes place under these circumstances.
What do primary alcohols oxidize to?
They oxidize to aldehydes
What do aldehydes oxidize to?
They oxidize to carboxylic acids
What do secondary alcohols oxidize to?
They oxidize to ketones
What can a secondary or tertiary alcohol be reduced to?
An alkane
What are the best oxidizing agents?
K2Cr2O7, KMnO4, H2CrO4, O2, Br2
What are the best reducing agents?
LiAlH4, NaBH4, H2 + Pressure
What is the general takeaway for good oxidizing agents?
Generally, a good oxidizing agent will have lots of oxygens
What is the general takeaway for good reducing agents?
Generally, they will have lots of hydrogen.
What is a good way to think about oxidation of a compound pertaining to the oxygen-to-hydrogen ratio?
If this ratio increases, then the molecule has been oxidized. If this ratio decreases, then the molecule has been reduced
What happens if a hydroxyl group is protonated by an acid?
It becomes water
Whats so special about water?
It's a good leaving group.
What's interesting to note about halide ions as nucleophiles?
They are weak bases, and do not become protonated in acidic solution.
So what happens if you add HX to teriary alcohol?
You will make an alkyl halide via Sn1.
What happens if you add HX to a methyl, primary, or secondary alcohol?
You will make an alkyl halide via Sn2.
When a C-O bond is broken in this reaction instead of the O-H bond, what is alcohol behaving as?
It is behaving as an electrophile.
A halogen ion, as a weak base, is a good or bad leaving group?
It is a good leaving group.
Is a hydroxyl group, as a strong base, a bad nucleophile?
No, it is a good nucleophile.
What happens when a hydroxyl group is protonated by an acid?
It becomes a water.
Is water a good leaving group?
It is an excellent leaving group.
Besides using a strong acid to convert an alcohol to an alkyl halide, what can be used?
Phosphorous halides such as PCl3 and PBr3, and PI3.
What type of mechanism is it?
It is an Sn2 mechanism.
Does it produce high or low yield with tertiary alcohols?
It produces poor yields with tertiary alcohols
What does thionyl chloride do when reacted with alcohols?
It produces alkyl halides from alcohols.
What is a sulfonate?
It is an ester formed from an alcohols.
What type of reaction is the formation of a sulfonate?
It is a nucleophilic substitution.
What acts as a nucleophile in the formation of a sulfonate?
The alcohol acts as a nucleophile.
Does the reaction proceed with inversion of configuration?
No, it proceeds with retention of configuration.
What are tosylates and mesylates?
They are commonly used sulfonates.
Are sulfonate ions good or bad bases?
They are very weak bases
Are they good or bad leaving groups?
They are excellent leaving groups.
When tosylates and mesylates are leaving groups, does the reaction proceed via an Sn1 or Sn2 mechanism?
It proceeds either way.
What is the pinacol rearrangement?
It is a dehydration of an alcohol.
What happens when hot sulfuric acid is added to an alcohol?
The expected product of dehydration is an alkene.
What is different about the pinacol rearrangement?
If the alcohol is a vicinal diol, it will form a ketone or aldehyde.
What happens to the first hydroxyl group of pinacol?
It is protonated and removed.
What does this removal form?
It forms a carbocation
What can the methyl group do thats interesting?
It can move to form an even more stable carbocation
What does the water do then?
It deprotonates one of the resonance hybrids, forming pinacolone and regenerating the acid catalyst.
So overall, what happens in the pinacol rearrangement?
You're taking a vinical diol, dropping a hydroxyl group, moving a methyl group to that spot, and forming a carbonyl on the other hydroxyl group.
Are ethers reactive or non-reactive?
Generally, except for epoxides, they are non-reactive
Are ethers polar?
Yes they are polar
Can they hydrogen bond with themselves?
No, they cannot.
Can they hydrogen bond with anything else?
They can hydrogen bond with compounds that contain a hydrogen attached to a N, O, or F atom
Are ethers as soluble in water as alcohols?
They are roughly as solube as alcohols of similar molecular weight.
Are organic compounds more or less soluble in ethers than alcohols?
They are more soluble in ethers.
no hydrogen bonds need to be broken in ethers.
What is the boiling point of an ether comparable to?
It is comparable to an alkane of similar size.
What do ethers other than epoxides undergo?
They undergo a reaction where they are cleaved by halo-acids to form a corresponding alcohol and alkyl halide
What do epoxides or oxiranes react with to produce diols?
They react with an acid catalyst to form diols.
What kind of diols do they form?
They form glycols, which exhibit anti-addition.
What is the weakest acid?
What is the next weakest acid?
Are alkynes the next weakest acid?
What is then?
Hydrogen gas
What is the next most acidic molecule after H2 gas?
What is next most acidic after Amines?
What is the most acidic group?
Carboxylic acids
What is the next most acidic group?
What is the next most acidic group after water?
What is the next most acidic group after alcohols?
What is the next most acidic group after aldehydes?
So what is the general trend of acidity?
Alkane < Alkene < H2 < NH3 < Alkyne < Aldehyde < Alcohol < H2O < Carboxylic Acid
Is the double bond of a carbonyl shorter or longer than the double bond of an alkene?
It is shorter than the double bond of an alkene.
Whenever you see a carbonyl on the MCAT, what two things should you think?
Planar stereochemistry and partial positive charge on the carbon.
What attacks the carbon of a carbonyl?
A nucleophile attacks the carbon
What types of carbonyls particularly undergo nucleophilic addition?
Aldehydes and ketones
What do the other carbonyl's prefer?
Nucleophilic substitution
What does the partial negative charge on the oxygen mean?
It means it is easily protonated
What is formaldehyde also known as?
What is acetone also known as?
Are aldehydes and ketones more or less polar than alkenes of similar weight?
They are more polar.
Do aldehydes and ketones have a higher or lower boiling point than alkenes of similar weights?
They have higher boiling points
Can aldehydes and ketones hydrogen bond with each other?
What does this infer about their boiling points pertaining to alcohols?
They have lower boiling points than alcohols of similar weight
Does this make aldehydes and ketones good or bad solvents for things that can hydrogen bond?
That makes them good solvents for things that hydrogen bond.
Aldehydes and ketones with how many carbons are soluble in water?
Aldehydes and ketones with up to four carbons are soluble in water.
What do aldehydes and ketones act as usually on the MCAT?
They usually act as the substrate in nucleophilic addition or as a Bronsted-Lowry acid by donating one of their alpha-hydrogens.
Are carbon anions good or bad bases?
They are very strong bases.
Are they stable?
Hell no
Well why are alpha carbons able to lose protons and normal carbons can't?
They can lose protons because they are stabilized by resonance.
What is it called when a carbon anion is stabilized by resonance via a carbonyl?
They are called enolate ions
What does a dicarbonyl do to the acidity of the alpha hydrogen between the carbonyls?
It increases the acidity because of the increased stabilization of the ion.
Why are aldehydes slightly more acidic than ketones?
They are more acidic because ketones have two alpha carbons, and they cause the ketone to be less able to distribute negative charge, decreasing stability of the ion.
This property do what to aldehyde reactivity versus ketone reactivity?
It makes aldehydes slightly more reactive than ketones.
Are ketones and aldehydes more or less acidic than alcohols?
They are less acidic than alcohol.
What does adding an electron withdrawing group to an alpha-carbon or the carbonyl do to the acidity?
Adding such a group stabilizes the conjugate base and increases acidity.
What do ketones and aldehydes exist at room temperature as?
They exist as tautomers.
How does the tautomerization involve a proton shift in this case?
It has one from the alpha-carbon position to the carbonyl oxygen position.
Is tautomerization a resonance or reaction at equilibrium?
It represents a reaction at equilibrium.
What do aldehydes and ketones react with alcohols to form?
They form hemiacetals and hemiketals.
In these reactions, what do the alcohols react as?
They react in typical fashion as nucleophiles.
What happens when aldehydes and ketones are attacked by a nucleophile?
They undergo addition.
What do aldehydes and hemiacetals exist as when an aldehyde is dissolved in an alcohol?
They exist in equilibrium.
What do ketones and hemiketals exist as when a ketone is dissolved in an alcohol?
They exist in equilibrium.
Are these hemiacetals and hemiketals stable or unstable, and what is a result of their stability?
They are too unstable to isolate unless they exist as ring structures.
What happens if a second molar equivalent of alcohol is added?
An acetal is formed from a hemiacetal, or a ketal is formed from a hemiketal.
How do you distinguish between the aldehyde products from the ketone products?
The aldehyde products have a lone hydrogen.
How can hemi products be distinguished from acetals and ketals?
Hemi products both have alcohols while the full acetals and ketals don't.
What is hemi formation catalyzed by?
It is catalyzed by an acid or base.
What must be protonated in the formation of acetal and ketal from hemi forms?
The hydroxyl group must be protonated to make a good leaving group.
Are acetals and ketals reactive or unreactive towards bases?
They are unreactive.
What does this make them useful for?
This makes them useful as blocking groups.
What would a base typically act as to attack an aldehyde or ketone at the carbonyl carbon?
A nucleophile
What does changing the aldehyde or ketone to an acetal or ketal accomplish?
It prevents the molecule from reacting with a base.
What happens when aldehyde or ketones are dissolved in aqueous solution?
They establish an equilibrium with their hydrate, a geminal diol.
So what happens in this reaction?
The oxygen on water attacks the carbonyl carbon, making geminal diols.
What happens during aldol condensation reactions?
It occurs when one aldehyde reacts with another, when one ketone reacts with another, or when an aldehyde reacts with a ketone.
What is this reaction catalyzed by?
It is catalyzed by an acid or base.
In the base-catalyzed reaction what occurs in the first step?
The base abstracts an alpha hydrogen leaving an enolate ion.
What happens in the second step?
The enolate ion acts as a nucleophile and attacks the carbonyl carbon to form an alkoxide ion.
Is this new alkoxide ion a stronger or weaker base than the hydroxide ion?
It is a stronger base
What does this infer it does?
It removes a proton from water to complete the aldol.
Is this aldol stable or unstable?
It is unstable
What happens when you add heat or a base to an aldol?
It makes an enal.
What is an enal stabilized by?
It is stabilized by its conjugate double bonds.
Halogens add to ketones at the alpha carbon in the presence of what?
Acid or base
What happens when a base is used?
It is difficult to prevent halogenation at more than one of the alpha positions.
Is the base consumed?
It is consumed by the reaction with water as a by-product.
Is the acid consumed?
No, it acts as a true catalyst by remaining throughout.
What happens when a base is used with a methyl ketone?
The alpha carbon will become completely halogenated.
What does this trihalo product react further with the base to produce?
It reacts with the base to produce a carboxylic acid and a haloform.
What are some examples of haloforms?
What is this reaction known as?
The haloform reaction.
What does the Wittig reaction do?
It converts a ketone to an alkene.
Wha tis used to accomplish this?
A phosphorous -ylide.
What is an -ylide?
It is a neutral molecule with a negatively charged carbanion.
What does the ketone act as first?
It acts as a nucleophile.
What does the nucleophilic addition to the ketone via the -ylide produce?
It produces a betaine.
Is the betaine stable or unstable?
It is unstable, and quickly breaks down to a triphenylphosphine oxide and the alkene.
Are the cis or trans isomers formed?
If possible, both cis and trans isomers will be formed.
What are alpha-beta unsaturated carbonyls?
They are carbonyls with a double bond between the alpha and beta carbon.
Is the carbocation stable or unstable?
It is very stable due to its resonance structures.
What does the electron withdrawing carbonyl do?
It pulls electrons from the double bond and makes it less susceptible to electrophilic addition.
What does this cause to happen rather than the electrophile adding to the double bonded carbon?
It may sometimes add to the oxygen, forming the enol-keto tautomers.
What can the beta carbon undergo directly?
The beta carbon can undergo nucleophilic addition directly.
What is this known as?
Conjugate addition
What is formic acid also known as?
Methanoic acid
What is acetic acid also known as?
Ethanoic acid.
What are carboxylic acids where the R group is an alkyl group called?
They are called aliphatic acids.
Salts of carboxylic acids are named with what suffix?
What does the -ate replace?
It replaces the -ic
What is an example of this?
Acetic becomes acetate
What is acetate sometimes abbreviated as?
What should you expect the carboxylic acid to behave as on the MCAT?
It should behave as an acid or as the substrate in a nucleophilic substitution reaction.
What does its stereochemistry make it susceptible to?
It makes it susceptible to nucleophiles.
What happens when the hydroxyl group is protonated?
The good leaving group, water, is formed and substitution results.
As far as organic acids go, are carboxylic acids strong or weak acids?
They are very strong.
Why are they such good acids?
When the proton is removed, the conjugate base is stabilized by resonance.
What do electron withdrawing groups on the alpha carbon act to do?
They help to further stabilize the conjugate base and thus increase the acidity of the corresponding carboxylic acid.
What's interesting about carboxylic acids hydrogen bonding ability?
They form strong double hydrogen bonds to form a dimer.
What does the dimer do to the boiling point?
It significantly increases the boiling point of carboxylic acids
How does it manage that?
It effectively doubles the molecular weight of the molecules leaving the liquid phase.
What phase are saturated carboyxlic acids with more than 8 carbons generally?
What do double bonds in unsaturated carboxylic acids do melting point?
They lower the melting point due how they impede the crystal lattice.
Are carboxylic acids with for carbons or less insoluble in water?
No, they are solube in water.
Are carboxylic acids with more than 10 carbons solube in water?
Are carboxylic acids soluble or insolube in most nonpolar substances?
They are soluble in most nonpolar solvents.
Why is that?
The dimer form allows the carboxylic acid to solvate without disrupting the hydrogen bonds of the dimer, allowing it do dissolve without breaking the hydrogen bonds.
What is it called when a carboxylic acid loses a CO2?
Are decarboxylations usually exothermic?
Are these easy or hard to carry out?
They are difficult due to a high energy of activation.
How can the energy of activation be lowered?
When the beta carbon is a carbonyl it becomes easier because the anion intermediate is stabilized by resonance or the acid forms a more stable cyclic intermediate.
What is a carboxylic acid called with a carbonyl beta carbon?
Beta-keto acid
What do derivates of carboxylic acids contain?
They contain the acyl group.
What do inorganic acid chlorides like SOCl2, PCl3, and PCl5 each react with carboxylic acids to form, and via what reaction type?
They form acyl chlorides, also called acid chlorides, via a nucleophilic substitution reaction.
Are acyl chlorides acid or bases?
They are Bronsted-Lowry acids
Where is the hydrogen donated from?
It is donated from an alpha hydrogen.
What does the electron withdrawing chlorine do to the conjugate base?
It stabilizes the base more than the lone hydrogen of an alhyde, making acyl chlorides significantly stronger acids than aldehydes.
Are acid chlorides reactive carboxylic acid derivatives?
They are the most reactive of the derivatives becuase of the stability of the Cl- leaving group.
What do acid chlorides love?
They love nucleophiles.
What does an acid chloride hydrolize to produce, and under what conditions?
It produces the carboxylic acid, typically under either acidic or basic conditions.
So what does adding H2O to an acid chloride produce?
A carboxylic acid
What does adding ROH to an acid chloride produce?
An ester
What does adding a RNH2 group to an acid chloride produce?
An amide
What does adding an RCOOH to an acid chloride produce?
An anhydride
What does taking any of the derivatives and adding water produce?
A carboxylic acid.
What do alcohols react with carboxylic acids to form?
They form esters
What type of reaction is this?
Nucleophilic substitution reaction
What does the strong acid do?
It catalyzes the reaction by protonating the hydroxyl group on the carboxylic acid.
How can the yield of the reaction be adjusted?
If you add more alcohol, it shifts to the right. If you add more water, it shifts to the left.
What is a more effective method for preparing esters?
To use an anhydride instead of a carboxylic acid to form the ester.
What do alcohols react in a similar way with esters to form?
It simply is the trading of alkoxy groups on an ester. The alcohol alkoxy group switches spots with the alcoxy group on the ester.
What is this known as?
What do beta-dicarbonyl compounds do to the acidity of the alpha hydrogens between the carbonyls?
They increase the acidity.
What is acetoacetic ester synthesis?
It is the production of a ketone from acetoacetic ester due to the strongly acidic properties of the alpha hydrogen.
What is added to remove the alpha hydrogens?
A base
What is the resulting molecule?
An enolate ion.
What happens to the enolate ion?
It is alkylated by an alkyl halide or tosylate leaving the alkylacetoacetic ester.
What can the alkylacetoacetic ester be decarboxylated by adding?
What is the final step of acetoacetic ester synthesis?
It is finished with the decarboxylation leaving the ketone.
What are amides?
They are formed when an amine, acting as a nucleophile, substitutes at the cabonyl of a carboxylic acid or one of its derivatives.
What are amines?
They are derivatives of ammonia.
What type of charge does nitrogen have when it makes 4 bonds?
It has a positive charge when it has 4 bonds.
Are amines Lewis acids or bases when they have a lone pair from 3 bonds?
They are Lewis bases, donating their lone pair of electrons.
Do amines act as nucleophiles or electrophiles when they have a lone pair from 3 bonds?
They act as nucleophiles where the lone pair of electrons attacks a positive charge.
Are ammonia and amines strong or weak bases?
They are weak bases.
What do electron withdrawing substituents do to the basicity of an amine?
They decrease the basicity.
What do electron donating substituents do to the basicity of an amine?
They increase the basicity.
What does steric hindrance created by bulky functional groups tend to do to the ability of an amine to donate its lone pair?
It hinders the ability to donate the lone pair.
The general trend for amine basicity is what?
2 > 1 > ammonia.
Are aromatic amines stronger or weaker bases than nonaromatic amines?
They are much weaker bases than nonaromatic amines.
The electron pair can delocalize around the benzene ring.
What do substituents that withdraw electrons from the benzene ring do to the basicity of the aromatic amine?
They further weaken it.
Given the shape of amines, would you expect some secondary and tertiary amines to be optically active?
I would.
Why is that not correct?
At room temperature the lone pair of electrons moves very rapidly from one side of the molecule to the other, inverting the configuration.
What does each chiral molecule spend equal time as?
It spends equal time as both enantiomers.
What types of amines can hydrogen bond with each other?
Ammonia, primary amines, and secondary amines can hydrogen bond with each other.
What amines can hydrogen bond with water?
All of them.
What does this do to lower molecular weight amines in water pertaining to their solubility?
It makes them very soluble in water.
Do amines with comparable molecular weights have higher or lower boiling points than alkanes?
They have higher boiling points.
Do amines with comparable molecular weights have higher or lower boiling points than alcohols?
They have lower.
What do amines react with aldehydes and ketones to produce via a loss of water?
They produce imines and enamines.
What are substituted imines sometimes called?
Schiff bases
What acts as a nucleophile in this reaction?
The amine acts as a nucleophile, attacking the electron deficient carbonyl carbon of the ketones..
What does the ketone undergo?
It undergoes nucleophilic addition.
What does an acid catalyst do?
It protonates the product to form an unstable intermediate.
What does the intermediate then lose?
It loses a water and a proton to produce either an anamine or an imine.
What happens if the original amine is secondary?
It will not have a proton to give up, so the ketone must give up its alpha proton.
What is the result of this?
An enamine is produced.
What if the original amine is primary?
It gives up its proton to form an imine.
So if you dump a primary amine in solution with a ketone or aldehyde, what do you make?
An imine
If you dump a secondary amine in solution with a ketone or aldehyde, what do you make?
An enamine
What happens if too much acid is used in the reaction?
The amine will become protonated before the first step.
What does this prevent?
It prevents the first step of the reaction from going forward.
What do imine and enamine exist as?
They exist as tautomers.
What happens to a ketone or aldehyde if you add hot acid in the presence ofamalgamated zinc (zinc treated with mercury)
You replace the oxygen of a ketone or aldehyde with two hydrogens.
What is this known as?
The Wolff-Kishner Reduction may be used instead.
What is the first step of the Wolff-Kishner Reduction?
It follows the same mechanism as imine formation, except a hydrazine is used instead of an amine.
What does the addition of hydrazine to the ketone or aldehyde produce?
It produces a hydrozone
What type of reaction is this?
Nucleophilic addition.
What is added to the hydrazone to deprotonate the nitrogen and produce the desired end-product?
Hot strong base should be added.
What type of solvent is usually used to faciliate the high temperature?
A high-boiling solvent.
So what is the overall point of the Wolf-Kishner Reduction?
To reduce an aldehyde or ketone to an alkane.
What can amines be alkylated with?
They can be alkylated with alkylhalides
What happens if you add R-X to an amine?
You end up adding the R group to the amine
What happens if you add R-X to NRH2?
You end up adding another R group to it, producing NR2H2.
What happens if you add R-X to NR2H2?
You add another R group to it, producing R3N
What happens if you add R-X to NR3?
You add another R group to it, producing R4N+
What type of reaction is this?
A nucleophilic substitution reaction.
What acts as the nucleophile?
The amine acts as a nucleophile.
What would be the point of converting an amine to a quaternary ammonium salt?
It is a much much better leaving group than -NH2.
What can be used to convert a quaternary alkyl halide to a quaternary ammonium hydroxide?
Silver Oxide works well.
What does heating the quaternary ammonium hydroxide result in?
It results in the Hofmann elimination.
What does this form?
An alkene.
Is the Hoffman product the most stable or least stable product?
It is the least stable product.
What is the most stable product?
The Saytzeff product is the most stable
Which predominates?
The less stable product, the Hoffman product, predominates
What can a strong acid do to nitrous acid?
It can dehydrate nitrous acid to produce nitrosonium ion and water.
What do primary amines react with nitrous acid to form?
They form diazonium salts.
What are aliphatic amines?
They are nonaromatic amines
Are they stable?
No they are extremely unstable.
What do they decompose spontaneously to form?
They form nitrogen gas.
Do aromatic amines form stable or unstable diazonium salts?
They form unstable diazonium salts
What type of amine can be used in the diazotization of an amine?
Only aromatic amines can be used because at low temperatures their spontaneous decomposition can be slowed.
What occurs via this reaction?
A primary aromatic amine creates a diazonium ion.
What can the diazonium group be replaced with?
It can be replaced with -OH, -X, -H, or -N=N-Ar
Can this occur with a secondary amine?
Why not?
Because it has an R group isntead of a tautomeric proton, which prevents the reaction from running to completion.
What are amides that have no substiuent on the nitrogen called?
They are called primary amides.
How are primary amides named?
They are named by replacing the -ic in the corresponding acid with amide.
What is formed when the -OH group of acetic acid is replaced by NH2?
What are substituents on the nitrogen prefaced by?
They are prefaced by N-.
Can amides behave as acids or bases?
They behave as weak acids and weak bases.
Are they more or less basic than amines?
They are less basic.
Due to the electron withdrawing properties of the carbonyl.
What are amides hydrolyzed by?
They are hydrolyzed by either strong acids or strong bases.
What are amides with a hydrogen attached to the nitrogen able to do?
They can hydrogen bond to another amide.
What are cyclic amides called?
They are called Beta-Lactams.
A beta-lactam has how many members on the ring?
4 members on the ring
How stable are amides compared to other carboxylic acid derivatives?
They are the most stable of the derivatives.
Are beta-lactams reactive or unreactive?
They are higly reactive due to large ring strain.
What easily reacts with beta-lactams?
Nucleophiles easily react with beta-lactams.
What are beta-lactams found in?
They are found in several types of antibiotics.
What do primary amides react with strongly basic solutions of chlorine or bromine to form?
They form primary amines with carbon dioxide as a by-product.
What is this reaction called?
It is called the Hofmann degradation.
What is the amide deprotonated by?
It is deprotonated by the strong base.
What is this product known as?
A N-haloamide.
Is the N-haloamide more or less acidic than the original primary amide?
It is more acidic.
What happens to the R group of the amide next?
It migrates to the nitrogen to form an isocynate.
What does this isocyanate react with water to form?
It forms a carbamic acid. What happens to the carbamic acid?
What is the advantage of using Hoffman elimiation versus other methods of producing amines?
The other methods rely on an Sn2 mechanism.
If you have a tertiary amine, can these Sn2 reactions take place?
What can the Hofmann degradation produces amines with?
It can produce amines with primary, secondary, or tertiary alkyl positions.
What is this reactiona sometimes called?
A hoffman rearrangement.
So overall, what happens?
The amide reacts to become an amine, keeping the original R-group by a rearangement during the reaction.
What does phosphoric acid look like?
It has a P in the middle, with 3 alcohol groups and a fourth double bonded oxygen group.
What happens do phosphoric acids when heated?
They form phosphoric anhydrides.
What do phosphoric acids react with alcohols to form?
They react with alcohols to form esters.
What are fatty acids?
They are long carbon chains with a carboxylic acid end
What do fatty acids serve the body to do?
They serve as hormones and intracellular messengers, they are components of the phospholipids and glycolipids of cell membranes, and they act as fuel for the body.
What are example of fatty acid intracellular messengers?
Eicosanoids such as prostaglandins.
What are fatty acids stored in the form of for fuel purposes?
What can triacylglycerols be hydrolyzed to form?
They can be hydrolyzed to form glycerol and the corresponding fatty acids.
What is this process known as?
What is this process the reverse of?
It is the reverse of esterification.
What can triacylglycerols be cleaved by?
By the addition of NaOH, they can be cleaved.
What is this process known as?
What is assigned the number one of these chains for nomenclature purposes?
The carbonyl carbon of the fatty acid is labeled one.
What is the carbon next to the carbonyl called?
It is called the alpha carbon.
What is the carbon at the opposite end of the chain called?
It is called the omega carbon.
What is the pKa of most fatty acids?
Around 4.5.
What does this infer about the state of fatty acids in the cellular environment?
Most fatty acids exist in their anion form in the cellular environment.
Can the carbon chains on fatty acids only be saturated?
No, they can be unsaturated or saturated.
Are fatty acids amphipathic?
What does this mean?
They contain a hydrophobic and hydrophilic end.
Because the hydrophobic carbon chains predominate, what does this make fatty acids?
What are fatty acids stored as?
They are stored as triacylglycerols.
Where are these held?
In adipose cells.
When does lipolysis of triacylglycerols take place inside the adipose cells?
It takes place when blood levels of epinephrine, norepinephrine, glucagon, or ACTH are elevated.
What happens to the resulting fatty acid products?
They are transported to different cells fo rthe utilization of their energy.
What happens to the fatty acid once inside the cell?
It is linked to Coenzyme A and its carried into the mitochondrial matrix by the gamma amino acid L-carnitine.
How many carbons at a time are fatty acids oxidized?
They are oxidized two carbons at a time
What does each oxidation yield?
Each yields an NADH, FADH2, and an acetyl CoA.
What does a peptide bond create?
It creates the functional group known as an amide
How it is formed?
It is formed via the condensation of two amino acids.
What is the reverse reaction of this?
The hydrolysis of a peptide bond.
What are the amino acids used by humans called?
Alpha-amino acids.
Why are they called that?
Becuase the amine group is attached to the carbon which is alpha to the carbonyl carbon.
What does the partial double bond character of peptide bonds prevent the bond from doing?
It prevents the peptide bonds from rotating freely.
What does this affect?
It affects the secondary and to some extent the tertiary structure of the polypeptide.
How many amino acids are essential?
10 are essential.
Generally, if the side chain of an amino acid contains a carboxylic acid, what type of amino acid is it?
It is acidic.
If if the side chain of an amino acid contains amines, what is it?
It is basic.
Are polar side group hydrophilic or hydrophobic?
They are hydrophilic.
What does this mean they will do in aqeous solution?
They will face an aqeous solution.
Are nonpolar side groups hydrophilic like polar side groups?
No, they are hydrophobic and will turn away from an aqeous solution.
What do these properties affect?
They affect a protein's tertiary structure.
What do amino acids exist as at low pH's?
They exist with an -OH group.
What do amino acids exist as at neutral pH's?
They exist as dipolar ions.
What are those also known as?
What do they exist as at high pH's?
They exist with an -O anion group.
What is the isoelectric point?
It is the point for any amino acid is the pH where the maximum number of species are zwitterions.
Where is it usually found?
It is found at the 1st equivalence of a titration.
How is this influenced by the acidity of the R group?
The more acidic the side group, the lower the pI. The more basic the side group, the greater the pI.
What is the formula for any carbohydrate?
What is the carbohydrate most likely to be on the MCAT?
Fructose or Glucose.
Both are six carbon carbohydrates called what?
Is glucose an aldehyde or a ketone?
It is an aldehyde
Is fructose an aldehyde or a ketone?
It is a ketone.
What are polyhydroxyaldehydes?
They are called aldoses
What is an example of a polyhydroxyaldehyde?
What are polyhydroxyketones like fructose called?
They are called ketoses
How else are carbohydrates named?
They are also named based upon the number of carbons they possess.
What are some examples?
Triose, tetrose, pentose, hexose, heptose, and so on.
What are the names commonly combined to call glucose?
They are combined to make glucose a aldohexose.
How do you determine when looking at Fischer projections if a carbohydrate is D or L?
If the hydroxyl group on the highest numbered chiral carbon points to the right, the carbohydrate is labeled D
What can the alcohol group on the chiral carbon farthest from the carbonyl act as?
It may act as a nucleophile and attack the carbonyl.
The attacked carbon is now called what?
An anomeric carbon.
What is a five-membered carbohydrate called?
It is called furanose
What is a six-membered ring called?
It is called pyranose.
What does glucose become?
It becomes glucopyranose.
Can the human body digest D or L carbohydrates?
It can digest only D carbohydrates.
What is Tollen's reagent?
It is used to detect aldehyde.
What do aldoses that have an aldehyde on their open-chain form do?
They reduce Tollens reagent.
What does Tollen's reagent promote?
It promotes ene-diol rearrangement of ketoses so that ketoses also reduce Tollens reagent.
What are glycosides?
They are sugars that are acetals
What do they end in?
They end in -osides
Do glycosides reduce Tollens reagent?
No they do not because they are closed ring, and only open ring compounds react with Tollens
What do nuclei with an odd atomic number or odd mass number exhibit?
They exhibit nuclear spin
What can this be observed by?
It can be observed by an NMR spectrometer.
What does this spin create?
It creates a magnetic field around the nucleus similar to the field created by a small magnet.
What happens when the nucleus is placed in an external magnetic field?
The nucleus aligns its own field with or against the external field.
Do nuclei aligned with the magnetic field have a higher energy state than those aligned against the field?
No, they have a lower energy state.
Which direction does an NMR increase?
It increase left to right.
What is the leftward direction called?
What is the rightward direction called?
Unless otherwise indicated, what is NMR concerned with?
What does each peak represent?
Each peak represents chemically equivalent hydrogens
What is splitting of peaks created by?
It is created by neighboring hydrogens
What are indistinguishable hydrogens also known as?
THey are known as enantiotropic.
What do enantiotropic hydrogens have?
They have the same chemical shift.
What do electron withdrawing groups do?
They tend to lower shielding and thus decrease the magnetic field strength at which resonance takes place.
Does this mean hydrogens with less shielding tend to have peaks downfield?
Yes, hydrogens with less shielding have frequencies downfield.
What do electron donating groups do?
They increase shielding and increase the required field strength for resonance.
What is the first step for NMR?
Identify the chemically equivalent hydrogens
What is the second step for NMR?
Identify and count neighboring hydrogens that are not chemically equivalent.
What is the shift for aldehyde?
9.5 ppm
Can a nucleus on Carbon-NMR have even atomic or mass numbers?
No, they must both be odd.
What is the IR stretch for -OH of a carboxylic acid?
What is the IR stretch for C=O?
What is the IR stretch for saturated C-H?
What is the IR stretch for aldehyde C-H?
2700, 2800
What is the IR stretch for -OH of an alcohol?
What is the IR stretch for N-H?
What is the IR stretch for Nitrile?
What does UV spectroscopy detect?
It detects conjugated double bonds.
What does UV start at with butadiene?
217 nm
For each additional conjugated double bond, the RV should increase by how much?
30 - 40 nm increase
What does mass spectrometry provide?
It provides the molecular weight
What is the peak made of molecular ions called?
It is called the parent peak
What is chromatography?
It is the resolution of a mixture by passing it over a surface that adsborbs the compounds within the mixture at different rates.
In column chromatography, do the more polar molecules travel faster or slower?
They travel slower down the column, creating separate layers for each compound.
In TLC chromatography, do the polar portions move faster or slower?
They move slowely because they are attracted to the polar plate.
In TLC chromatography, what moves fastest?
Non-polar moves fastest.
Do nonpolar components have an Rf factor close or far from one?
They have Rf factors that are close to one.
What is distillation?
It is separation based upon vapor pressure.
The compound with a lower boiling point (higher vapor pressure) will do what first?
It will boil first and be captured.
What is an azeotrope?
It is a solution with an exact ratio of the two liquids.
Can an azeotrope be separated by distillation?
What is fractional distillation?
It is a more precise method of distillation.
What is crystallization?
It is based upon the principle that pure substances form crystals more easily than impure substances.
Is crystallization of most salts an endothermic process?
No, it is an exothermic process.
Is crystallization an effecient method for separating two things?
No, it is very inneficient.
What is extraction?
It is based upon solubility due to similar polarities.
What is the first step for extraction?
Add a strong acid and shake.
What does adding a strong acid do?
The acid protonates bases like amines in the organic layer, making them polar.
What do the polar amines do?
They dissolve in the aqueous layer and are drained off.
What do you do next?
Add a weak base.
What does adding a weak base do?
The base deprotonates only the strong acids like carboxylic acids, making them more polar.
What do you do last?
Add a strong base.
What does adding a strong base do?
It reacts with the rest of the acids such as Phenol.